Field of the Invention: The present invention relates to circuit board eyelets and particularly relates to circuit board eyelets for flexibly interconnecting electrical circuitry on opposite surfaces of a circuit board through a hole in the circuit board.
Description of the Prior Art: Circuit boards having conductive patterns on opposite surfaces thereof are well-known in the electronics packaging arts. Through-hole connectors for flexibly interconnecting such conductive patterns on opposite surfaces of a circuit board are described in U.S. Pat. Nos. 2,966,652; 3,268,652; 3,361,869; 3,452,149; 3,484,935 and 3,846,743. All of the above patents are directed to the problem of providing a flexible through hole connector. A flexible connector is required to prevent thermal cycling of the printed circuit board during manufacture and use from stressing and fracturing the soldered connections to the conductive patterns on opposite surfaces of the circuit board. In addition to the flexible connectors described in the above-mentioned patents, eyelet connectors have also been used for connecting conductive patterns on opposite surfaces of circuit boards. Eyelet connectors are described in U.S. Pat. Nos. 3,368,188; 3,504,328; 3,601,786 and 3,654,583. These eyelet connectors comprise a flanged end, an annular body and a plurality of staking legs. Although the flange in such eyelets has been adapted to provide improved resistance to stress failure of the soldered connection on opposite surfaces of a circuit board, the annular body is substantially rigid and does not provide a truly flexible through hole connector. However, the truly flexible through hole connectors described in the afore-mentioned patents have been impractical and unsatisfactory for various reasons, e.g. due to the cost of materials, the requirement for expensive and complicated fabrication apparatus, complicated assembly steps requiring extensive manual labor and the lack of readily available machines for applying the connectors to a circuit board.